storeFileLocally adds duplicate file extension when a filename is provided

[kissle]

Hello @NyllRE,

thank you for this awesome package.

I found a minor issue with the filenames created in the storeFileLocally method. When you actually provide a filename it takes the filename and add the file extension. So a file called data.json will be stored as data.json.json.

When one doesn't expect a certain name it's probably not a big deal. In my case it causes the need for some special handling.

I could locate the issue to following lines in storage.ts:

const filename =
    typeof fileNameOrIdLength == 'number'
	? `${generateRandomId(fileNameOrIdLength)}.${originalExt}`
	: `${fileNameOrIdLength}.${originalExt}`

In my eyes it looks unintentional to add the originalExt in the alternative path of the statement. It would be enough to return fileNameOrIdLength.

Thank you! Alex